Holcim green built ,Bangladesh

status:competition,2010

honorary prize

The goal of the project is to make a self sustaining pod house for the mostly poverty stricken population of Bangladesh who are living in the marsh lands(haors) or lands annually affected by floods , water surges ,cyclones or similar natural  calamities.

The pod practically creates more green area than it destroys, meaning ,if we consider the amount of green area & vegetation the pod adds up to the land, is more than the  footprint it requires to be erected. The pod is supported by a hollow pre-cast, pre-stressed concrete tube which also transports water collected from the ground through filtering by osmosis system & discharges waste to the central bio-gas plant. The height of the tube is adjusted depending on flood or water surge levels for location specific conditions to protect the pod from the elements.

The pod is targeted to fulfill just enough ergonomics & amenities to squeeze in to a very compact prototype solution for habitation that is both individual and also capable of forming clusters & communities. In fact when these pod houses are operating in unison they are better fitted to the environment (e.g. clusters create scope for bio-gas plants & excess solar energy that can be shared within the community, not to mention the community advantages).

The pod is designed to form groups so that social events, community activities

Flourish to make a more interactive & supportive community. The internal shaded courts & alleys can hold small informal bazaars, play areas etc.

The pod has basically 4 parts, the base cum reservoir, the service unit, the living unit & the roof top garden & solar panel unit. Internal planning is informal- free space for multiple uses during day & night time activities. For cross ventilation there are operable full height louvered windows made of bamboo. One of which can be lowered to make an out door deck. The remaining parallel walls are solid to give maximum thermal protection. This minimizes the need for additional cooling.

The toilets can use grey water collected & filtered from the roof garden while kitchens can use bio-gas generated from the waste & sewage collected from other pods within the cluster. This helps reduce dependency on external fuel & energy. The solar panels would help to drive water pumps, run radios or other communication, emergency or electronic devise.

Construction: The general assumption about concrete is that it is not an environ friendly material, but some considerations are given to ratify that concrete can be also a green material when intuitively & intelligently used, it follows as below-

Designing for sustainability accounts in the design a short-term and long-term effect of the societal & environmental impact. Therefore, durability is the key .In particular, to build in a sustainable manner means to focus attention on physical, environmental, and technological resources, problems related to human health, energy conservation of new and existing buildings, and control of construction technologies and methods

The most of the pod is made of pre-cast Ferro cement panels which require less concrete and is lightweight for assembly & transportation. Ferro-concrete has been widely used specially for pre fabricated overhead water reservoirs in the southern part of Bangladesh especially for its durability to withstand salinity & water penetration not to mention itsthermal properties.

Ferro cement uses wire meshes for reinforcement that reduces use of steel & makes the structure economic & light weight.

Concretes great simplicity lies in the fact that its constituents are ubiquitous and are readily available almost anywhere in the world. As a result of its ubiquity, functionality and flexibility it has become by far the most popular and widely used construction material .The ingredients are proportioned and engineered to produce a concrete of a specific strength and durability, so it is ‘fit for purpose’ for the job for which it is intended.

Ferro cement can be a sustainable building material despite the energy consumed during the manufacture of the cement component. Its inherent properties and the local sourcing are also key factors in the overall sustainability of the construction works. Whole life costing (WLC) takes account of total cost of an item over its whole life. It includes the cost of maintaining and operating the item and is a mechanism to deliver improved value for money. It helps reduced cost in the medium and long term, reduced risk. Ferro concrete is considered to prove very effective as it has around 50years or more lifespan.

Re using concrete debris & masonry rubble can be profitably treated and reused for preparing mortars for new construction replacing the need of new course aggregates. Containing masonry rubble up to 25-30% aggregate for mortars, allowed excellent bond strengths.

Industrial by-products such as fly ash and slag due to their highly pozzolanic and cementitious properties can be used. Use of coal fly ash in concrete started in the 1930s, and volcanic ash has been recycled for several millenniums in mortar and concrete (in Egypt, Italy, Mexico, India, and other places). Recycling minimizes solid waste disposal, improves air quality, minimizes solid wastes, and

leads to sustainable cement and concrete industry.

In the production of concrete it is estimated to be 2.07 GJ/m3 or 0.89 MJ/kg. Replacing 10% of the Portland cement with fly ash reduced this to 1.94 GJ/m3 or 0.83 MJ/kg.

Post-consumer wastes and industrial by-products can be and must be used in concrete to make “greener” concrete. Glass, plastics, Pulp and paper mill residual solids, tires, foundry sand and wood fibers can be used for applications specific, high-quality, durable aggregates.

 CO2 absorption capabilities of concrete are beginning to be fully understood.  Furthermore, concrete’s durability, thermal efficiency, acoustic performance, fire resistance, and storm water management applications, will ensure its contribution to a sustainable building.

We cannot create or destroy matter; we can only affect how it is organized, transformed, and used. By obeying the rules we can make Ferro-concrete a well sustainable building material for the building industry as a whole.